Here's a piece of my current Makefile:
CFLAGS = -O2 -Wall -pedantic -std=gnu++11 `sdl-config --cflags --libs` -lSDL_mixer
If the header file is
/usr/include/sdl/SDL.h and your code has:
You need to either fix your code:
Or tell the preprocessor where to find include files:
CFLAGS = ... -I/usr/include/sdl ...